Noise transmitting on a power supply line causes malfunction to a circuit board in which digital, analogue and RF mixed circuit, SOC (system on chip), pseud-SOC and etc. are mounted. In order to prevent the malfunction, it is proposed to provide a filter using a microstrip line or three dimensional EBG (Electromagnetic Band Gap) structure.
However, it is required that a ground plane, which is to be a reference plane, should come close to the microstrip line. Therefore, a restriction on the arrangement of the filter will be enhances. In addition, a filter pattern with small area capable of cutting low frequency signals has not been realized yet. Thus, it leads to the problem in miniaturization of a circuit board, etc.
In addition, it is necessary to avoid three dimensional structure when forming a connection part such as a through via in three dimensional EBG structure. In addition, an EBG structure with small area capable of cutting low frequency signals has not been realized yet. Thus, it leads to the problem in miniaturization of a circuit board, etc. Thus, it leads to the problem in miniaturization of a circuit board as well.